Possible Clues:

• Supports a move to have the incentive raised
• Run in to disturb son's footholds
• Horse riders put their feet in them
• Put your foot in them for a rider
• Where the cavalry get footholds
• They are important to one's standing as a rider
• Loops for the rider's feet
• Rider's footrests
• They'll give you a leg-up
• Rider's rests cause trouble, then spur breaks